[v1,28/33] libcamera: dw100_vertexmap: Implement parametric dewarping
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Message ID 20250930122726.1837524-29-stefan.klug@ideasonboard.com
State New
Headers show
Series
  • Full dewarper support on imx8mp
Related show

Commit Message

Stefan Klug Sept. 30, 2025, 12:26 p.m. UTC
Implement functions to allow lens dewarping based on the common lens
dewarp model used e.g. by OpenCV

See https://docs.opencv.org/3.4/da/d54/group__imgproc__transform.html#ga7dfb72c9cf9780a347fbe3d1c47e5d5a

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
---
 .../converter/converter_dw100_vertexmap.h     | 17 ++++
 .../converter/converter_dw100_vertexmap.cpp   | 87 +++++++++++++++++++
 2 files changed, 104 insertions(+)

Patch
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diff --git a/include/libcamera/internal/converter/converter_dw100_vertexmap.h b/include/libcamera/internal/converter/converter_dw100_vertexmap.h
index 9c6e0ffa4513..7a12c4cb7a50 100644
--- a/include/libcamera/internal/converter/converter_dw100_vertexmap.h
+++ b/include/libcamera/internal/converter/converter_dw100_vertexmap.h
@@ -12,6 +12,9 @@ 
 #include <libcamera/geometry.h>
 #include <libcamera/transform.h>
 
+#include "libcamera/internal/matrix.h"
+#include "libcamera/internal/vector.h"
+
 namespace libcamera {
 
 class Dw100VertexMap
@@ -57,11 +60,20 @@  public:
 	void setMode(const ScaleMode mode) { mode_ = mode; }
 	ScaleMode mode() const { return mode_; }
 
+	int loadDewarpParams(const YamlObject &dict);
+	int setDewarpParams(const Matrix<double, 3, 3> &cm, const Span<const double> &coeffs);
+	bool dewarpParamsValid() { return dewarpParamsValid_; }
+
+	void setLensDewarpEnable(bool enable) { lensDewarpEnable_ = enable; }
+	bool lensDewarpEnable() { return lensDewarpEnable_; }
+
 	std::vector<uint32_t> getVertexMap();
 
 private:
 	int getVerticesForLength(const int length);
 
+	Vector<double, 2> dewarpPoint(const Vector<double, 2> &p);
+
 	Rectangle scalerCrop_;
 	Rectangle sensorCrop_;
 	Transform transform_ = Transform::Identity;
@@ -75,6 +87,11 @@  private:
 	double effectiveScaleY_;
 	Point effectiveOffset_;
 	Rectangle effectiveScalerCrop_;
+
+	Matrix<double, 3, 3> dewarpM_ = Matrix<double, 3, 3>::identity();
+	std::array<double, 12> dewarpCoeffs_;
+	bool lensDewarpEnable_ = true;
+	bool dewarpParamsValid_ = false;
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/converter/converter_dw100_vertexmap.cpp b/src/libcamera/converter/converter_dw100_vertexmap.cpp
index 10d9e34d98c5..5581d53e57c7 100644
--- a/src/libcamera/converter/converter_dw100_vertexmap.cpp
+++ b/src/libcamera/converter/converter_dw100_vertexmap.cpp
@@ -66,6 +66,14 @@  Vector2d point2Vec2d(const Point &p)
 	return { { static_cast<double>(p.x), static_cast<double>(p.y) } };
 }
 
+void transformPoint(const Rectangle &from, const Rectangle &to, Vector2d &p)
+{
+	double sx = to.width / static_cast<double>(from.width);
+	double sy = to.height / static_cast<double>(from.height);
+	p.x() = (p.x() - from.x) * sx + to.x;
+	p.y() = (p.y() - from.y) * sy + to.y;
+}
+
 } /* namespace */
 
 /**
@@ -344,6 +352,17 @@  std::vector<uint32_t> Dw100VertexMap::getVertexMap()
 			p.x() += localScalerCrop.x;
 			p.y() += localScalerCrop.y;
 
+			if (dewarpParamsValid_ && lensDewarpEnable_) {
+				/*
+				 * We are in localScalerCrop coordinates.
+				 * Tranform to sensor coordinates.
+				 */
+				transformPoint(localScalerCrop, effectiveScalerCrop_, p);
+				p = dewarpPoint(p);
+				/* tarnsform back to localScalerCrop */
+				transformPoint(effectiveScalerCrop_, localScalerCrop, p);
+			}
+
 			/* Convert to fixed point */
 			uint32_t v = static_cast<uint32_t>(p.y() * 16) << 16 |
 				     (static_cast<uint32_t>(p.x() * 16) & 0xffff);
@@ -354,6 +373,74 @@  std::vector<uint32_t> Dw100VertexMap::getVertexMap()
 	return res;
 }
 
+int Dw100VertexMap::loadDewarpParams(const YamlObject &dict)
+{
+	Matrix<double, 3, 3> m;
+	const auto &cm = dict["cm"].get<Matrix<double, 3, 3>>();
+	if (!cm) {
+		LOG(Converter, Error) << "Dewarp parameters are missing 'cm' value";
+		return -EINVAL;
+	}
+
+	m = *cm;
+
+	const auto &coeffs = dict["coefficients"].getList<double>();
+	if (!coeffs) {
+		LOG(Converter, Error) << "Dewarp parameters 'coefficients' value is not a list";
+		return -EINVAL;
+	}
+
+	const Span<const double> span{ *coeffs };
+	return setDewarpParams(m, span);
+}
+
+int Dw100VertexMap::setDewarpParams(const Matrix<double, 3, 3> &cm, const Span<const double> &coeffs)
+{
+	dewarpM_ = cm;
+	dewarpCoeffs_.fill(0.0);
+
+	if (coeffs.size() != 4 && coeffs.size() != 5 &&
+	    coeffs.size() != 8 && coeffs.size() != 12) {
+		LOG(Converter, Error) << "Dewarp 'coefficients' must have 4, 5, 8 or 12 values";
+		dewarpParamsValid_ = false;
+		return -EINVAL;
+	}
+	std::copy(coeffs.begin(), coeffs.end(), dewarpCoeffs_.begin());
+
+	dewarpParamsValid_ = true;
+	return 0;
+}
+
+Vector2d Dw100VertexMap::dewarpPoint(const Vector2d &p)
+{
+	double x, y;
+	double k1 = dewarpCoeffs_[0];
+	double k2 = dewarpCoeffs_[1];
+	double p1 = dewarpCoeffs_[2];
+	double p2 = dewarpCoeffs_[3];
+	double k3 = dewarpCoeffs_[4];
+	double k4 = dewarpCoeffs_[5];
+	double k5 = dewarpCoeffs_[6];
+	double k6 = dewarpCoeffs_[7];
+	double s1 = dewarpCoeffs_[8];
+	double s2 = dewarpCoeffs_[9];
+	double s3 = dewarpCoeffs_[10];
+	double s4 = dewarpCoeffs_[11];
+
+	y = (p.y() - dewarpM_[1][2]) / dewarpM_[1][1];
+	x = (p.x() - dewarpM_[0][2] - y * dewarpM_[0][1]) / dewarpM_[0][0];
+
+	double r2 = x * x + y * y;
+	double d = (1 + k1 * r2 + k2 * r2 * r2 + k3 * r2 * r2 * r2) /
+		   (1 + k4 * r2 + k5 * r2 * r2 + k6 * r2 * r2 * r2);
+	x = x * d + 2 * p1 * x * y + p2 * (r2 + 2 * x * x) + s1 * r2 + s2 * r2 * r2;
+	y = y * d + 2 * p2 * x * y + p1 * (r2 + 2 * y * y) + s3 * r2 + s4 * r2 * r2;
+
+	Vector2d ret{ { x * dewarpM_[0][0] + y * dewarpM_[0][1] + dewarpM_[0][2],
+			y * dewarpM_[1][1] + dewarpM_[1][2] } };
+	return ret;
+}
+
 int Dw100VertexMap::getVerticesForLength(const int length)
 {
 	return (length + kDw100BlockSize - 1) / kDw100BlockSize + 1;